The present invention generally relates to a method to capture a physically consistent snapshot of data that is from an Online Transaction Processing system. The online transaction processing system is derived from a remote database backup system, which is maintained by (i) transferring a package of audit data from a primary database system to a remote system process; (ii) then writing the audit data to a remote disk; (iii) then applying the audited changes to the remote database backup copy. When a network communication error occurs during the first step (i) involving transferring a package of audit data from a primary database to a remote system process, then, the primary database system activity is temporarily suspended as a QUIESCE point.
The process of suspending database update activity is counterproductive to the goal of maintaining 24×7×365 database update availability and thus constitutes a problem. In this regard, if a physically consistent database “copy” could be created from an online remote database system, then production database availability for updates will be improved while system performance is also improved when a remote physically mirrored snapshot is used to offload processing.
In order to accomplish the physically consistent snapshot just described, a database system process, or “QUIESCE” operation, according to the present invention, consists of a database utility command that communicates a “QUIESCE” request to an online remote database whereby a series of processes are initiated which allows “Read” access to the secondary host database copy.
When the QUIESCE command is issued to a remote database backup system, the results are as follows: (1) the utility program DMUTILITY that issues the QUIESCE command calls a RDB Support Library procedure at the remote host which sends a message to the primary host Accessroutines program via a network transmission, (2) the primary host Accessroutines waits for all active/update transactions to complete, (3) future transactions are suspended on the primary host database, (4) data and audit buffers of the primary host database are written to disk, (5) the primary host Accessroutines writes two specialized “control points” to the audit file, (6) primary host database update activity is automatically resumed, (7) the audit blocks containing the two specialized control points are sent to the secondary host via the Remote Database Backup audit transfer mechanism, (8) the secondary host Tracker Task reads the two specialized control points from the audit trail, (9) the secondary host Tracker Task writes all data buffers to disk, (10) the QUIESCE status and QUIESCE TIMESTAMP—captured from the specialized control points—are written to the control file at the secondary host, (11) the database utility program completes with the message “DATABASE QUIESCED,” (12) the secondary host Tracker Task is suspended while read access is allowed to the secondary host database copy until a database utility RESUME command is entered at the secondary host.
One prior art method to which the method of the present invention generally relates is described in U.S. Pat. No. 6,421,717, entitled “System, Method, And Computer Program Product For Customizing Channels, Content, And Data For Mobile Devices”. This prior art method includes systems, methods, computer program products, and combinations and sub-combinations thereof, for enabling web content (as well as other objects) to be loaded on mobile devices (as well as other types of devices), and for users of mobile devices to operate with such web content on their mobile devices in an interactive manner while in an off-line mode.
The present invention differs from the above prior cited art in that the present invention focuses on capturing a physically consistent snapshot of data that is from an Online Transaction Processing system, while guaranteeing logical and physical consistency of data snapshots. Unlike the prior art method, the present invention supplies “remote” methods that involve remote disk configuration, and therefore, no additional disk configuration is required at the primary host. The method of the present invention provides a function to read the timestamp value from the specialized control point audit record, and store this value into the QUIESCE TIMESTAMP location of the database control file at a secondary host.
Yet another prior art method to which the method of the present invention generally relates is described in U.S. Pat. No. 6,341,316 entitled “System, Method, And Computer Program Product For Synchronizing Content Between A Server And A Client Based On State Information”. This prior art method includes systems, methods, computer program products, and combinations and sub-combinations thereof, for enabling web content (as well as other objects) to be loaded on mobile devices (as well as other types of devices), and for users of mobile devices to operate with such web content on their mobile devices in an interactive manner while in an off-line mode.
The present invention differs from the above prior cited art in that the present invention focuses on capturing a physically consistent snapshot of data that is from an Online Transaction Processing system, while guaranteeing logical and physical consistency of data snapshots. Unlike the prior art method, the present invention supplies “remote” methods that involve remote disk configuration, and therefore, no additional disk configuration is required at the primary host.
Yet another prior art method to which the method of the present invention generally relates is described in U.S. Pat. No. 6,332,146 entitled “Method And Apparatus For Storing And Printing Digital Images”. This prior art method involves a digital data management and order delivery system. The system includes a storage device for storing digital data and a searching engine for developing a subset of the digital data stored in the storage device in response to inputs received from a first user. The system is also provided with a job order developer responsive to inputs received from the first user for developing a job order which includes: a) at least one copy of the digital data contained in the subset and identified by the first user; and b) a file containing information developed by the first user outside the system. In addition, the system includes a router for electronically routing the job order compiled by the job order developer to a second user specified by the first user.
The present invention differs from the above cited art in that this method of the prior art teaches methods that control the storage of data from a database module. The method of the present invention contrarily solves the problem of capturing a copy of data, which is both physically and logically consistent while the methods taught by the above patent teaches methods to capture data (or objects) without any regard to physical and logical consistency.
Yet another prior art method to which the method of the present invention generally relates is described in U.S. Pat. No. 6,131,088 entitled “Electronic Catalog System And Method”. This prior art method is a method for accessing product information data and detecting pirated copies of a serialized software program. This includes transmitting a data request query related to a selected product from a remote computer to a main computer, identifying a subset of product data related to the selected product stored in the memory of the main computer based on the data request query, transmitting textual data from the subset of product data from the main computer to the remote computer, transmitting only updated graphics data from the main computer to the remote computer, and combining the textual data received from the main computer with graphics data stored in the memory of the remote computer to provide complete product information data related to the selected product. These methods also include storing a program serial number, the remote revision level corresponding to the program serial number, and a validation code for a remote program corresponding to the serial number. The methods detect whether the program stored in the remote memory is valid or invalid based upon the validation code corresponding to the program serial number.
The present invention differs from the above prior art in that the method of the present invention provides a feature of using a Remote Database Backup audit trail (a.k.a. transaction log) to determine a point of database consistency, and of capturing a physically consistent mirrored snapshot of an online database from a remote database backup system.
Yet another prior art method to which the method of the present invention generally relates is described in U.S. Pat. No. 6,029,142 entitled “Electronic Catalog System And Method”. This prior art method is an apparatus and method provided for displaying product information data related to at least one product. The method includes the steps of transmitting a data request from the remote computer to the main computer, transmitting the variable data and display information from the main computer to tie remote computer, transmitting updated constant data from the main computer to the remote computer, and storing the updated constant data in the memory of the remote computer. The method also includes the steps of integrating constant data stored in the memory of the remote computer with the variable data received from the main computer and using the display information received from the main computer to format the constant data and the variable data to generate the product information data related to the product, and displaying the product information data generated by the remote computer during the integrating step on a monitor coupled to the remote computer.
The present invention differs from the above prior art in that the method of the present invention provides functions and purposes which the method of the prior art does not. The method of the present invention provides a function to suspend the remote audit application process (a.k.a. Tracker) after two requested “control points” are read from the audit trail whereby physical consistency is achieved through the flushing of data memory buffers to disk. The method of the present invention also provides a function to send a network message from a secondary host to a primary host database to request the two specialized control points.